1. Field of the Invention
This invention relates to spring mattress strips and, more particularly, to a strip structure made of plastic material with a reduced intrinsic weight and a high flexibility, which enables it to support relatively heavy loads without suffering permanent deformations.
2. Description of the Related Art
Spring mattresses made of plastic strips having the objective to provide a support, which under the load of a human body at rest adopts a perfectly horizontal disposition, are already known. It has been scientifically verified that beneficial effects are obtained, by using these strips for the prophylaxis of complaints affecting the spinal column.
On the other hand, the condition of "comfort" of this type of spring mattress is determined by the flexibility of the support, i.e., by the capacity of deformation thereof under light loads. Consequently, the spring strips for this type of mattress should be capable of being deformed elastically and to adopt a disposition, which should be as horizontal as possible under the load conditions of a human body at rest. For this purpose, strips made of flexible material should have a certain convexity in order to absorb the deformations caused by the load.
In addition, the resistance of the strips of this type, which are used to form spring mattresses, should not only be calculated for supporting the load of the human body at rest, but it should also have the necessary dimensions for supporting much heavier loads, for the event of misuse made by the users, and even for high peak loads, without suffering permanent deformations.
Another technical limitation for the material, of which the strips are to be made, is determined by the relatively low weight requirements of a spring mattress, which requires the use of strips as light as possible. In the past, only strips made of wood, either massive or plywood, having a compact structure with a determined convexity, are known. The utilization of wood, either massive or plywood, represents as such a strong limitation to the object proposed for these spring mattresses, because wood is an anisotropic material, wherein the typical problems caused by the accumulation of shearing and carving stresses (weak points) are produced. In addition, this lack of homogeneity causes undesired deformations of "warping", particularly due to the humidity absorption.